Apparatus to adjust the tension of a material web that is moved through a processing station processing the material web

Abstract

In order to be able to adjust the tension and position of a material web, for example, a paper web, that should be printed by a printer, an electrostatically-acting braking device is described that provides a charger, for example, a corotron, and a braking plate, between which the material web runs. The charger charges the material web, which is thereby drawn to the braking plate, lies on the braking plate, and is braked via friction. It is advantageous that the charge voltage of the charger and be controlled via sensors for the web tension and web position and can very quickly react to the signals of the sensors.

Description

BACKGROUND OF THE INVENTION[0001]The adjustment of the tension of a material web is always of importance when the material web must be processed exactly. A typical example is an electrographic printing device in which a recording medium is printed as a material web in a printing group. Such electrographic print devices are presumed in the following discussion.[0002]In such an electrographic print device, a clean / faultless print image is only created when the material web (e.g., a paper web) is supplied to the printing group of the print device in a taut, pre-stressed state. For this, it is known from German Patent Document No. DE 197 49 603 C2 to provide a loop-puller device via which the material web is guided. The loop-puller device comprises a loop-puller roller, under spring tension and movable in a predetermined region, via which the material web is stressed.[0003]In normal operation, the deflection of the loop-puller roller is sufficient to keep the material web stressed. Howe...

AI Technical Summary

Benefits of technology

This solution ensures stable web tension and position, reducing mechanical effort and enabling rapid regulation, maintaining consistent processing results across different material web types and widths, with the ability to adjust braking force and position accurately.

Problems solved by technology

However, there are situations in which additional measures are necessary in order to keep the material web in a stressed state.

However, there are problems with the use of a negative pressure brake as a braking device when, for example, the material web is corrugated or comprises holes (material webs with marginal perforations).

What is particularly problematic is mutual influencing of the parameters, i.e., upon change of the web position, a change of the web tension or the web tension distribution over the width of the material web results.

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